The present invention relates to liquid crystal displays generally, and more particularly an improved thin film transistor array panel.
A liquid crystal display (LCD) is one of the most widely used flat panel displays. An LCD includes two panels provided with field-generating electrodes and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer, which determines orientations of LC molecules in the LC layer which adjusts the polarization of incident light.
A conventional LCD provides a a narrow viewing angle. Various techniques for increasing the viewing angle have been suggested. In particular, one technique uses a vertically aligned LC and provides cutouts or protrusions at each field-generating electrodes. The cutouts and the protrusions reduce the aperture ratio. Therefore, there is a need to maximize the pixel electrode size. However, the closeness of the pixel electrodes causes strong lateral electric fields to form between them. The lateral electric fields dishevel orientations of the LC molecules and produce spots and light leakage. In turn, the spots and light leakage deteriorate overall display performance.
A LCD using cutouts or protrusions offers an excellent viewing angle, over 80 degrees in any direction. However, such a LCD has poor visibility, inferior even to a twisted nematic mode LCD. In a LCD using cutouts, discordance of the gamma curve between the front view and side view causes poor visibility.
For example, in a vertically aligned LCD using cutouts, the picture plane becomes brighter and the color shifts toward white as the viewing angle increases. When this phenomenon is excessive, the picture image is distorted because the brightness difference between gray scales disappears. A solution is needed that provides LCDs with improved visibility.